Arc chute side with encapsulated face wound blowout coil



F. J. POKORNY Nov. 3, 1964 3 Sheets-Shet 1 Filed Dec. 2l, 1960 2 2 5 ,wf/b 2 w7 JTlT d 2%@ f 0 L 00.00 A /e i 6 7 a a 7 a a a/ 5 w 3 i 5 6 a@DHI M M d W L4 f f P 4 a s 5 y lllllllllllll F. J. PoKoRNY 3,155,801

ARC CHUTE SIDE WITH ENCAPSULATED FACE WOUND BLOWOUT COIL Nov. 3, 1964 5Sheets-Sheet 2 Filed Dec. 2l, 1960 INVENTOR. FAm/K. a, PaA/a/P/Vy Nov.3, 1964 F. J. PoKoRNY 3,155,801

ARC CHUTE SIDE WITH ENCAPSULATED FACE WOUND BLOWOUT COIL Filed Dec. 21,1960 3 Sheets-Sheet 3 *e L x WWWW 25a 25, .,86

United States Patent O 3,155,801 ARC CHUTE SIDE WITH ENCAPSULATED FACEWOUND BLWDUT CGL Frank i. Polrorny, Hatboro, la., assigner to I-T-ECircuit Breaker Company, Philadelphia, Pa., a corporation ofPennsylvania Filed Dec. 21, 1960, Ser. No. 77,432 4 Claims. (Cl. 20G-147) My invention relates to circuit breakers and more particularly to acircuit breaker are chute having a novel arrangement for encapsulating ablowout coil.

It is well known in the power distribution field to provide circuitbreakers for system protection. Circuit breakers presently in use aredesigned to interrupt the circuit being protected within a few cycles.

When the contacts of the circuit breaker start to disengage, the voltagedrop between the separating contacts causes an arcing condition whichdelays interruption time, effects the power factor of the system andvaporizes the separating contacts. For this reason circuit breakers havebeen provided with accompanying are chutes to cause a rapidextinguishment of the arc.

The arc chutes of the prior art are provided with: blowout means to urgethe arc drawn between the beaker contacts deeply into the are chute; arcplates which subject the arc to a tortuous path for rapid extinguishmentf the arc; and arc runners to which the arc is transferred from theseparating contacts under the influence of the blowout means. The arcchute must -be built to Withstand conditions of severe heat and theimpact of expadded gases which are generated by the tripping operationof the circuit breaker. The arc chute must also be designed to provideadequate support for the blowout coil, the 4arc plates and the arcrunners. In order to embody these features into the arc chute, prior artdevices required separate means for positioning retaining 'and isolatingthe blowout coil, the arc plates and the arc runner. The blowout meansof the prior art further required U-shaped iron cores to concentrate themagnetic field generated by the blowout coil in the regio-n of theseparating breaker contacts. Additional means then had to be includedwith the arc chute to give the arc chute adequate mechanical strength towithstand the stress imposed on the arc chute. Construction of such arechutes, therefore, required a great deal of material and expense.

My invention consists of two lightweight shells which, when fastenedtogether, form the arc chute. Each shell is molded of a material havinghigh dielectric and mechanical strength. Integ'ral with the outer faceof each shell is an annular shaped trough in which the blowout coil isembedded. A plurality of supporting ribs positioned a spaced vdistanceapart within the trough act to separate the blowout coil from the basinof the trough. An insulating filler material is poured into the troughto cement the coil firmly into place. A plurality of spaced horizontalribs secured to the outer surfaces of each shell and adjacent the troughlend added mechanical strength to the trough. This added reinforcementis necessary to rigidly secure the blowout coil due to the extremelylarge magnitude force of the magnetic field generated by the blowoutcoil during short circuit or overload conditions.

The inner face of each shell contains two spaced parallel ribs which arevertically aligned and integrally mounted to the inner face. Thevertically aligned ribs act to position the arc plates of the are chute.A horizontal ledge integral with the inner face of each shell serves tosupport the arc plates.

The blowout coils mounted in each trough are electrically connected inseries aiding fashion by means of conductive pins, which pins aresecured by the inner walls of the shells.

The magnetic tields generated by lCe the blowout coils aid one anotherthereby generating a magnetic lield of great strength.

The shells are secured to one another by inserting fastening meansthrough vertically aligned apertures on each shell to form a sturdy arechute housing.

Due to the manner in which the blowout coils are secured in my novel arcchute, there is no need for an iron core for the purpose ofconcentrating the magnetic eld, thus resulting in an arc chute which islighter in weight and which does not require the mechanical strengththat is needed in arc chtues presently in use.

However, iron may be used in my novel arc chute where it is desired tostrengthen the magnetic field or to concentrate the magnetic tield in aportion of the area described by the blowout coil. Due to the novelconfiguration of my arc chute the iron may be incorporated into the arcchute without changing the present contiguration of the arc chute.

It is, therefore, one object of my invention to provide a novel arcchute requiring fewer parts than are chutes presently being used.

Another object of my invention is to provide a novel arc chute havingface wound blowout coils.

Another object of my invention is to provide an arc chute with a novelmeans for encapsulating a blowout coil.

Still another object of my invention is to provide an arc chute housinghaving a novel trough for positioning and securing the blowout means.

Another object of my invention is to provide a novel light-weight arcchute which has great mechanical strength.

These `and other objects will become apparent in the followingdisclosure and drawings of which:

FIGURE l is a perspective view of my novel arc chute showing thecooperating shells in disconnected position.

FIGURE 2 is a side plan View of the front shell shown in FIGURE l.

' FIGURE 3 is a cross-section taken along phantom line 3-3 of FIGURE 2.

FIGURE 4 is a schematic view showing the novel arc chute of my inventionmounted to a circuit breaker.

FIGURE 5 is a perspective schematic view of my novel arc chute showingthe electrical connections of the facewound blowout coils.

Referring now to FIGURES l, 2 and 3, the arc chute designated as 23comprises two shells 53 and 54. The shells 53 and Y54 are molded of amaterial having high dielectric and mechanical strength. The outer faceof shell 54 has an irregularly shaped trough 64 formed between portions82 and 83 which extend outward from the face of plate 54. A blowout coil30 is seated in the trough as shown in FIGURES 2 and 3. Although coil 30is shown as having only one turn, it should be understood that a greaternumber of turns may be used. One terminal of coil Sti is electricallyconnected to a pin 28, while the other terminal of winding 30 iselectrically connected to pin 31. The functions of pin 28 and 31 will bemore fully described in connection with FIGURES 4 5.

The iioor 74 of trough 64 contains a number of supporting ribs 65 whichserve to elevate coil 30 a small distance above the floor of trough 64.A filler material 66 (see FIGURE 3) is then poured into the trough. Afiller material 66 having excellent insulating and bindingcharacteristics, such as a high dielectric epoxy, is used to rigidlysecure winding 30" within trough 64. Reinforcing ribs 61 and 63 whichare formed integrally with shell 54 aid trough 64 in rigidly securingcoil 30 during the tripping operation. Reinforcing ribs 61 and 63 extendin a horizontal direction as viewed in FIGURES 1 and 2. Coil 30 carriesseveral thousand amperes during an overload or short circuit conditionwhich current generates an intense magnetic eld. The magnetic fieldurges coil 30 outward against the outer wall 70 of trough 64.Reinforcing ribs 6-1and 63 provide adequate strength to trough 64 toprevent the coil from changing its configuration -under the influence ofthe magnetic field. The outer face of shell 53 has a configuration whichis the mirror image of the outer face of shell 54. That is, the outerface of shell 53 contains a trough (not shown in the drawings) havingthe same .shape as 'trough 64. The outer face of shell 53 also hasreinforcing ribs which are mirror images of reinforcing ribs 61 and 63of shell 54.

Shells 53 and 54 each have a plurality of apertures 62 spaced alongoutwardly turned flanges 71 and 72, respectively. The apertures 62 ofshell 53 are in alignment with the corresponding apertures 62 of shell54 to permit fasteners such as bolts to be inserted therethrough andsecured with associated nuts to form a rigid arc chute housing 23.

FIGURE 3 is a cross-section of shell 54 taken along the line 3 3 ofFGURE 2. FIGURE 3 shows coil 30 positioned in trough 64 and resting onribs 65, only one of which is shown in FIGURE 3. The filler material 66is permitted to surround coil 30, thereby supporting and positioning itfrom the side walls 73 and floor 74 or ri-b 65 of trough 64. A pair ofvertical ribs 86 are positioned along the inner face 75 of shell 54.Ribs 86 position a plurality of spaced parallel arc plates 24 (seeFIGURE 4) as will be more fully described. A horizontal ledge 67 whichis integral with inner face 75 acts as the suppor means for the areplates 24. v

The plurality of spaced parallel arc plates 24, as best seen in theschematic View of FIGURE 5, are positioned between the two shells 53 and54 between the right and left vertical ribs 86, and on the horizontalledge 67. Thus, shells 53 and 54 prevent the arc plates 24 from movinglaterally with respect to the arc chute 23. The vertical ribs 86 limitthe movement of the arc plates 24 in the extreme right or leftdirection, and the horizontal ledge 67, on which the arc plates 24 canrest, limits the downward movement of the plates 24.

Referring now to the schematic views of FIGURES 4 and 5, the arc chute23 is shown operatively positioned upon a circuit breaker. Arc chute 23is supported upon a circuit breaker by means of connector pin 32 securedto arc chute 23 and seated in support bracket 20 which bracket iselectrically connected to upper terminal 11. The mechanical electricalconnecting bracket is described in detail in my copending U.S.application Serial No. 77,433, filed December 2l, 1960, entitledMechanical and Electrical Pivot Between Removable Arc Chute andStationary Contact Structure, and assigned to the same assignee as theinstant application. It should be understood, however, that 'the arcchute of this application does not rely upon the structure of bracket 20for its novelty but the bracket 20 is set forth merely as one manner ofconnecting the arc chute to a circuit breaker.

The circuit breaker consists of main 19 and arcing 19a contacts whichare secured to upper terminal 11 by means of side plates 21. A movablebridge 16 is pivotally connected to lower terminal 12 at pivot 42 andoperated between its open and closed positions by push rod 40'. Mountedupon bridge 16 are butt contacts 18 and 17 which engage main 19 andarcing 19a contacts, respectively, when movable bridge 16 is in theclosed position (not shown in the drawings).

Blowout coils 29 and 30 (shown by phantom lines) are embedded in thefaces of side walls 53 and 54, respectively, as described in thedescription of FIGURES 1 and 2. Terminal 55 of blowout coil 29 iselectrically connected to conductive pin 23; the ends of pin 2S areembedded in the inner faces of side walls 53 and 54. A rear arc runner25 having its upper portion secured to are chute 23 in any well-knownmanner, is electrically connected to pin 23 at it lwer portion 26. Theother terminal 56 of coil 29 is electrically connected to conductive pin31 the ends of which are secured by the inner walls of faces 53 and 54.Blowout winding 30 embedded in face 54 of arc chute 23 has one terminal57 electrically connected to pin 31 and the other terminal 5Selectrically connected to conductive pin 32 which is secured to arcchute 23 in the same maner as pins 28 and 31 described above. Arc plates24 are supported by horizontal ledge 67 and are restrained fromlengthwise movement by vertical ribs 86. The mounting of arc runners 25,25a and arc plates 24 plays no part in the novelty of this invention andmay be carried out in any well known manner such as, for example, as setforth in US. Patent No. 2,761,934 entitled High Voltage Circuit Breakersissued September 4, 1956, to l. D. Wood et al. or U.S. Patent No.2,941,060 entitled Arc Extinguishing Means for High Voltage CircuitBreakers, issued June 14, 1960, to A. S. Caswell, the assignee of bothpatents being the same as the assignee of the instant application.

Upon the occurrence of a short circuit or overload condition, movablebridge 16 rotates clockwise about pivot 42 under control of push rod 40.Due to the voltage drop across arcing contacts 17 and 19a, an arc A isformed therebetween. The heat generated by the arc, combined with theblow-off effect causes arc A, which is drawn between arcing contacts 17and 19a, to transfer to the lower portion 26 of rear arc runner 25 andthe lower portion 26a of front arc runner 25a. The arc now assurnesposition B shown in FIGURE 4.

The current path at this instant is: lower terminal 12, conductive strap41, arc runner 25a, arc B, conductive pin 28, coil 29, conductive pin31, coil 36, conductive pin 32, conductive support 20 and upper terminal11. In tracing this path it can be seen that coils 29 and 30 areconnected in serial fashion so that the magnetic fields generated bycoils 29 and 30 will aid one another to produce a resultant magneticfield tending to urge the are B deeply into arc chute 23.

It should be noted that the configurations of blowout coils 29 and 30are such that a non-homogeneous magnetic iield is generated by the coilsZ9 and 30 during the tripping operation initiated by either an overloador short circuit condition. Referring to FIGURE 2, it can be seen thatarea 81 within coil 30 forms an acute angle which serves to concentratea large amount of magnetic flux in this area. It can be seen in FIGURE 4that this portion of greater tiux density is in the immediate region ofarcing contacts 17 and 19a. The high density magnetic field generated inthe region of arcing contacts 17 and 19a by coils 29 and 30 serves totransfer the arc as shown in position A of FIGURE 4 upward along arcrunners 25 and 25a at a very rapid rate.

The arc, under the influence of the magnetic field generated by coils 29and 30, moves upward along arc runners 25 and 25a into the region of arcplates 24. Arc plates 24 provides a tortuous path for the upward movingarc, causing it to be extinguishedy very rapidly.

Iron may be used in cooperation with the arc chute in order tostrengthen the flux density of the magnetic field generated by theblowout coil. FIGURE 5 shows an iron plate Sil having the configurationof the blowout coil. The iron plate S0 causes the magnetic flux to beconcentrated in the lower half of the blowout coil loop thus increasingthe magnetic force impressed upon an arc drawn in the region ofseparating contacts 17 and 19a causing the arc to be urged rapidly intothe arc chute 23. The iron plate S0 may be mounted to the arc chute 23by placing iron plate 80 in the area 81 (see FEGURES 1 and 2) betweenthe trough 64 and rib 63. The iron is rigidly held in place by usingfiller material (not shown) of the same type used to encapsulate blowoutwindings v29' and 30. An iron plate may also be mounted on the outerface of side wall 53 of the arc chute 23. The filler material avoids theneed for bolts or other fastening means.

lt can be seen from the foregoing description that I have provided anarc chute which is simple in design and which requires fewer parts,thereby simplifying its fabrication and reducing its cost of production.The novel manner in which the blow-out coils are positioned and securedcompletely avoids the need for the iron core guide paths necessary inthe prior art.

Although I have described preferred embodiments of my novel invention,many variations and modifications will now be obvious to those skilledin the art, and I prefer therefore to be limited not by the specilicdisclosure herein but only by the appended claims.

l claim:

l. An arc chute for interrupting an electric arc comprised of a pair ofshells; each of said shells being made of a material having highdielectric strength and having a plurality of apertures spaced along itsperimeter; fastening means inserted through said apertures for securingsaid shells to one another to thereby form a partially enclosedsubstantially rectangular housing; each or said shells having an innerand outer face; said outer faces of each of said shells having iirst andsecond extending portions projecting outward from said outer face ofsaid shells; said first and second extending portions forming an annularshaped trough therebetween; blowout means for urging an electric arcinto said housing; said blowout means including rst and second coilseach having at least one turn; said first coil being positioned in saidtrough of one of said shells and said second coil being positioned insaid trough of the other of said shells; each of said coils formed togenerate magnetic flux in both the region of cooperating contacts andsubstantially the entire region of said arc chute; said inner face ofeach of said shells having a pair of spaced parallel ribs verticallyaligned in said shell; a plurality of spaced parallel arc plates; saidarc plates being positioned between said ribs and within the housingformed by said pair of shells; filler material contained in each of saidtroughs to rigidly secure said coils to their associated said shells.

2. The device of claim 1 having a horizontal ledge on said inner tace ofsaid shells for supporting said arc plates within said housing.

3. An arc chute for interrupting an electric arc comprised of a pair ofshells; each of said shells being made of a material having highdielectric strength and having a plurality of apertures spaced along itsperimeter; fastening means inserted through said apertures for securingsaid shells to one another to thereby form a partially enclosedsubstantially rectangular housing; each of said shells having an innerand outer face; said outer faces of each ot said shells having first andsecond eX- tending portions projecting outward from said outer face ofsaid shells; said first and second extending portions forming an annularshaped trough therebetween; blowout means for urging an electric arcinto said housing; Said blowout means including lirst and second coilseacr having at least one turn; said first coil being positioned in saidtrough of one of said shelis and said second coil being positioned insaid trough of the other of said shells; each of said coils formed togenerate magnetic flux in both the region of cooperating contacts andsubstantially the entire region of said arc chute; liller materialcontainedv in each of said troughs to rigidly secure said coils to theirassociated shells; said annular shaped trough forming a depressed areaat the lower portion thereof on said outer face of said shells; an ironplate; said iron plate positioned in said depressed area to strengthenthe iiux density of the magnetic lield generated by said first andsecond coils; filler material contained in said depressed area torigidly secure said iron plates.

4. in combination, a pair of cooperating contacts; an arc chutepositioned to interrupt an electric arc drawn between said pair ofcooperating contacts upon separation thereof; said arc chute comprisinga partially enclosed housing; blowout means on said housing operativelypositioned for urging said arc into said arc chute; said blowout meansincluding a coil having a conliguration to generate a non-homogeneousmagnetic eld; an outer surface of said housing having first and secondextending portions projecting outward from saio1 outer surface of saidhousing; said lirst and second extending portions forming an annularshaped trough therebetween for securing said coil to the said outersurface of said housing and for positioning said coil to generate amagnetic field in the region of both said cooperating contacts andsubstantially the entire region of said arc chute and further toconcentrate the portion of said magnetic lield having the greatest fluxdensity in the immediate region of said cooperating contacts to transfersaid arc rapidly trom said cooperating contacts to said arc chute; llermaterial contained in said trough to rigidly secure said cOil to saidhousing; an iron plate positioned within the inner periphery deiined bysaid trough for concentrating the magnetic ield generated by said coilin the region of said cooperating contacts; tiller material contained inthe region defined by the inner periphery of said trough to rigidlysecure said iron plate to said housing.

References Cited in the iile of this patent UNITED STATES PATENTS2,147,430 Ellis et al Feb. 14, 1939 2,381,637 Bohn Aug. 7, 19452,564,178 Strobel Aug. 14, 1951 2,777,036 Frink et al Jan. 8, 19573,024,331 Frink Mar. 6, 1962

1. AN ARC CHUTE FOR INTERRUPTING AN ELECTRIC ARC COMPRISED OF A PAIR OFSHELLS; EACH OF SAID SHELLS BEING MADE OF A MATERIAL HAVING HIGHDIELECTRIC STRENGTH AND HAVING A PLURALITY OF APERTURES SPACED ALONG ITSPERIMETER; FASTENING MEANS INSERTED THROUGH SAID APERTURES FOR SECURINGSAID SHELLS TO ONE ANOTHER TO THEREBY FORM A PARTIALLY ENCLOSEDSUBSTANTIALLY RECTANGULAR HOUSING; EACH OF SAID SHELLS HAVING AN INNERAND OUTER FACE; SAID OUTER FACES OF EACH OF SAID SHELLS HAVING FIRST ANDSECOND EXTENDING PORTIONS PROJECTING OUTWARD FROM SAID OUTER FACE OFSAID SHELLS; SAID FIRST AND SECOND EXTENDING PORTIONS FORMING AN ANNULARSHAPED TROUGH THEREBETWEEN; BLOWOUT MEANS FOR URGING AN ELECTRIC ARCINTO SAID HOUSING; SAID BLOWOUT MEANS INCLUDING FIRST AND SECOND COILSEACH HAVING AT LEAST ONE TURN; SAID FIRST COIL BEING POSITIONED IN SAIDTROUGH OF ONE OF SAID SHELLS AND SAID SECOND COIL BEING POSITIONED INSAID TROUGH OF THE OTHER OF SAID SHELLS; EACH OF SAID COILS FORMED TOGENERATE MAGNETIC FLUX IN BOTH THE REGION OF COOPERATING CONTACTS ANDSUBSTANTIALLY THE ENTIRE REGION OF SAID ARC CHUTE; SAID INNER FACE OFEACH OF SAID SHELLS HAVING A PAIR OF SPACED PARALLEL RIBS VERTICALLYALIGNED IN SAID SHELL; A PLURALITY OF SPACED PARALLEL ARC PLATES; SAIDARC PLATES BEING POSITIONED BETWEEN SAID RIBS AND WITHIN THE HOUSINGFORMED BY SAID PAIR OF SHELLS; FILLER MATERIAL CONTAINED IN EACH OF SAIDTROUGHS TO RIGIDLY SECURE SAID COILS TO THEIR ASSOCIATED SAID SHELLS.